I am using an '87 vette IFS and IRS under my Opel project, however I am building a custom chassis to keep everything together vs the factory cross members.

That is the best I can help with. Both kits appear to be simple and straight forward. If the geometry is correct, then they would make an excellent IFS for your truck.

The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me